Priority is claimed under 35 USC xc2xa7119(a) based on Japanese Patent Application Serial No. 2001-243661 filed Aug. 10, 2001.
This invention relates to four-cycle engines having as a fuel source a gas-lubricant mixture and in particular it relates to the manner of lubricating certain of the components of the engine.
The benefit of using a gas-lubricant fuel source for a four-cycle engine is that certain of the moving parts, e.g., the actuating mechanism for the intake and exhaust valves, can be placed in the flow path of the fuel for lubrication thereof. This is particularly beneficial for small engines which are operated in all manners of positions and wherein the oil bath form of lubrication that is typical for four-cycle engines is not practical.
In such engines there are nevertheless moving parts that are not so readily lubricated. An example is the cam gear shaft which is journalled at its ends in the walls of the engine. It is conventional for the journalling of such shafts to mount the shafts in bearings, e.g., roller or ball bearings and such bearings are an added expense which could be diminished if instead the shafts were mounted in lubricated bushings.
The present invention provides an engine design wherein at least one of the journalled components is journalled in the vicinity of the fuel flow and ports are strategically positioned to provide fuel flow as required to lubricate the component. This obviates the need for bearings and reduces the cost of manufacturer without sacrificing wear life of the engine.
The various ways for providing fuel-lubricant to the bushing of the journalled components will be further appreciated and understood upon reference to the following detailed description having reference to the accompanying drawings.